Investigate

Investigate is the final stage of exploration, and typically follows approach, though with some stimuli, an animal can switch directly from a search behavior to Investigate. Investigate serves to provide animals information about the focal stimulus.

Investigatory behaviors differ according to the sensory modality the animal is using. However, in mice, investigation is typically multi-modal, and primarily involves olfactory and tactile senses.

• Sniffing (olfactory investigation). The mouse makes rapid twitching movements of the nose, either with the nose in contact with the stimulus, or held in an elevated position in the air (see variants, below).
• Whisking (tactile investigation). With the whiskers in contact with the stimulus, the mouse rapidly brushes the whiskers along the surface and edges of the stimulus.

Exploration

Exploration occurs in three main contexts: Social, Food, and Environmental. However, the context is not normally apparent until the investigation stage of the behavior chain. Context is determined by the nature of the stimulus investigated:

1. Social. The stimulus investigated is another mouse.
2. Food. The stimulus investigated is a potential food item.
3. Environmental. The stimulus investigated is a non-food object in the environment, or the mouse performs investigative sniffing while not in contact with a potential stimulus (typically seen in conjunction with rearing).

• Investigate - Stretched Attend. This characteristic posture is performed when the animal investigates a potentially dangerous stimulus. It may occur in social, food and environmental contexts.
• Investigate - Body Trunk. This, or stretched-attend, is typically the first social investigation behavior performed.
• Investigate - Facial. Investigation of the facial region. Social context only.
• Investigate - Anogenital. Investigation of the anogenital region. Social and sexual behaviors contexts.
• Investigate - Object. Investigation of an object. Food, or environmental contexts.
• Investigate - Undirected Sniffing. Investigation not directed to a specific stimulus. Environmental context only.